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First Global Map Outside the Solar System
First time accepted submitter Kreuzfeld writes "For many years, astronomers have suspected that brown dwarfs — 'failed stars' with masses between those of planets and stars — have cloudy atmospheres. Our recent paper in Nature presents the first global, 2D map of the patchy clouds in the atmosphere of a brown dwarf: our neighbor, the 6.5 light-years-distant Luhman 16B. Eventually, astronomers will use this technique to make weather movies of global cloud patterns on brown dwarfs and extrasolar planets."
How is this a "global map" ? It seems at best to be an "atmospheric" map, which I'm sure is interesting although usually a bunch of clouds that never stop moving.
+1 insightful
The red version is much better.
The large scale structure seems to stretch between the poles, at fairly constant longitude, rather than around the axis at fairly constant latitude, like every other atmosphere we've encountered. Is there some reason they are really that way, or is it some artifact of the data gathering and rerduction?
Those people who think they know everything are a great annoyance to those of us who do. (Isaac Asimov)
Except for the vast orders of magnitude difference in which speed at which the two move, you're almost correct.
(name withheld by request)
This map is 6.5 years old already.
This is why I love Slashdot: Comments by the scientists involved! Thanks for your hard work guys!
The brown dwarf they imaged was found only a few months ago, yet it is only 6.5 light years away, using data from WISE. This fact, along with the very productive results from the Kepler mission, make me hopeful that our knowledge of our neighbourhood in the Milky Way can greatly improve in the next few decades so long as we continue funding specialized space-based telescopes.
The actual mapping was done using ground-based telescopes. I found this description of how they accomplished the mapping quite interesting:
http://www.mpia.de/Public/menu_q2.php?Aktuelles/PR/2014/PR_2014_02/PR_2014_02_en.html
How did the researchers manage to reconstruct a surface map, and how did they uncover the layer structure?
With current technology, it is not possible to produce surface maps of this brown dwarf (or other distant stars and brown dwarfs) in the same way that we would, say, map the cloud bands of Jupiter, namely by directly taking images that show all the details.
The indirect technique used instead is called Doppler imaging. It makes use of the fact that light from a rotating star is slightly shifted in frequency as the star rotates. From the systematic shifts, an approximate map of the stellar surface can be reconstructed.
For a rough picture of how this happens, imagine that you are hovering high above the Earth's equator, watching the globe spin beneath you. As an object sitting on the equator comes into view, it will first move toward you while crossing the horizon and coming into sight; as it passes directly beneath you, its distance from you will change very slowly, and as it passes across your horizon out of sight, it will move away from you at speed. An object placed at higher latitudes (that is, shifted towards one of the poles) will follow a similar pattern, but at overall lower speeds. An object situated at one of the poles will not move towards you or away from you at all as the Earth rotates.
Now imagine the same situation for a brown dwarf. When a bright spot rotates into sight, the way it moves directly towards or away from you will depend on latitude, while the timing of when it rotates into and out of sight defines its longitude. And while astronomers cannot follow the spot's travels directly, there's the so-called Doppler shift: Light will change its wavelength very slightly depending on whether, and how fast, the emitting object is moving towards or away from the observer. Combining the Doppler shift patterns hinting at latitude with timing carrying information about longitude, the astronomers can attempt to reconstruct the brown dwarf's surface pattern. The reconstruction involves some ambiguity and uncertainty, but the result shown here is the most probably surface structure deduced from the many Doppler measurements made by Crossfield et al.
Will it be possible to import this map into Starcraft? A DLC, even?
As there are different types of dwarf planets (such as brown dwarf), what different types are there and how do we differentiate from them?